Section 15.3 Looping through nodes
Often the XML has multiple nodes and we need to write a loop to process all of the nodes. In the following program, we loop through all of the user nodes:
Checkpoint 15.3.1.
What do you think this code will print? Run it to see what it actually prints.
import xml.etree.ElementTree as ET
input = '''
<stuff><users><user x="2"><id>001</id><name>Chuck</name></user><user x="7"><id>009</id><name>Brent</name></user></users></stuff>'''
stuff = ET.fromstring(input)
lst = stuff.findall('users/user')
print('User count:', len(lst))
for item in lst:
print('Name', item.find('name').text)
print('Id', item.find('id').text)
print('Attribute', item.get('x'))
The findall method retrieves a Python list of subtrees that represent the user structures in the XML tree. Then we can write a for loop that looks at each of the user nodes, and prints the name and id text elements as well as the x attribute from the user node.
Checkpoint 15.3.2.
Put the following blocks in order to use a loop to process nodes in an XML program, like the one seen above.
Use findall to retrieve subtrees representing user structures in the XML tree.
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Use a for each loop to loop through the user nodes
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Print the name and id from the user node
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Print the x attribute from the user node using get
It is important to include all parent level elements in the findall statement except for the top level element (e.g., users/user). Otherwise, Python will not find any desired nodes.
Checkpoint 15.3.3.
What do you think this code will print? Run it to see what it actually prints.
import xml.etree.ElementTree as ET
input = '''
<stuff><users><user x="2"><id>001</id><name>Chuck</name></user><user x="7"><id>009</id><name>Brent</name></user></users></stuff>'''
stuff = ET.fromstring(input)
lst = stuff.findall('users/user')
print('User count:', len(lst))
lst2 = stuff.findall('user')
print('User count:', len(lst2))
lst stores all user elements that are nested within their users parent. lst2 looks for user elements that are not nested within the top level stuff element where there are none.
Checkpoint 15.3.4.
